Fluorochemical compounds are well know and commercially used to coat or render various substrates oil- and water repellent and to provide other desirable properties thereto such as soil repellency and soil release.
Fluorochemical sulfonamido silanes having at least 4 carbon atoms in the fluoroalkyl group have been described for treating substrates in GB 2,218,097; U.S. Pat. Nos. 5,274,159; 5,702,509; and earlier in 3,492,394; 3,423,234, and 3,442,664.
In addition, fluorochemical oligomeric silanes having at least 4 carbon atoms in the fluoroalkyl group have been described for treating hard surfaces, such as glass or ceramics in EP 1,369,453; EP 1,225,187, and EP 1,225,188.
Despite the many known fluorochemical compositions to provide repellency properties to a substrate, there continues to be a desire to find further compositions that may have improved initial repellency properties and/or that have improved durability, i.e., the repellency properties last longer even under abrading conditions.
Accordingly, it is desirable to provide a coating composition capable of providing a highly durable water, oil and/or stain repellent coating on a substrate. In particular, it is desirable to provide a durable coating wherein the initial, repellent properties are substantially maintained, even under abrading conditions. Further, the coating compositions preferably can be applied and used in an environmental friendly way and can be produced in a reliable, convenient and cost effective way. Additionally, the coatings desirably have a good durability against exposure to UV light, i.e. the repellency properties do not substantially degrade upon exposure to UV light. Furthermore, it is desirable to obtain optically clear coatings in particular when transparent substrates such as glass are to be treated with the compositions.